Tire retreading device



Nov.v 26, 1946. H. v. JAMES 2,411,687

TIRE RETREADING DEVICE Original Filed July 24, 1944 2 Sheets-Sheet l Nov. 26, 1946.v H. V. JAMES I TIRE RETREADING DEVICE original Filed July 24, -1944 v 2 Sheets-Sheet 2 INVENTOR. HAROLD l/ J/z/k/fs.

ATTORNEY.A

Patented Nev. 26, 1946 l UNITED STATE s PATENT;v OFFICQ- l.TIRE .RETREADING DEVICE( y v v f Harold V. James, Denver,'Colo. I i A *original application July 24, 19.44, serial No.'

f 546,266. rDivided and this application July 9,

A.1945, Serial No. 603,817

- comms. (01.18-18) Otherobjects of the invention aretovprovide means' vfor supporting` a'mechanical pressure device for casing vulcanizers so that `it'may be easily handled by` one man regardless of its weight; to providermechanic'al means for expandilllga tirecasing into a matrix mold in which a ,maximumV expanding action vmay be hadwith a l minimum of effort; toprovide an expansible re- `silienirring which when-expanded into the casing by the mechanical pressured'evice will uniformly f distribute the pressure over theentireinternal surface regardless ofv irregularities"therein.'i

Other objects and advantages residey inthe detail Aconstruction of the invention ,gwhich isde- Vsigned for simplicity, economy; `and efficiency. These will becomermore apparent fromV the following description'. l1 .y

In thek followinggdetailed description of the invention, reference is hadgto the accompanying drawings which form a part hereof. Like numeralsrefer to like parts in all views vof the drawings and throughoutthe' description.

Inthe drawingsd Y Figil is a side view cf'the improved tire re- '.'tr'eadn'g device, illustrating the latter in the closed. position,.ready for use., In this view the open position of th 'mold is indicated in broken imac isa' cross-section'rthicugnthe moidhous- 'Line taken pn the, nne 24,2, Fig. 1. .lFig. '3ds' asimilar .cross-,section takenvvonv the line `3-3,.Fig. 1. p Y,

Fig. 4,is a vertical cross-section through the y improved retreading device taken on the line 4?4,Fig.1. y Fig.5 is'ja'fragmentary perspective view ofthe interior Vof the Vmold housing. y p

Fig 6 is a detail perspective view illustrating the method. of; mounting a mechanical pressure shoeonits actuating arms, as'used in this device. "Fig. 7' isa detail sectionallvew through the xed bracket bearing for the jack screw employed arbe, innove@message device-- 1 2 In Fig. 4 only the top and bottom pairsof radial pressure shoe arms have beenillustrated. `'Ihe remainder have been omitted to clarify the illustration. f

The improved retreading device is designed to support a tirevcasing in a vertical position and to apply mechanical expanding `pressure to the interior of the tire casing to force it outwardly against an external, heated mold face. f l

The device comprises a circular, hollow housing formed in three sections, a lbase section I0 an'dtwo hinged sections II'. The base section I Ii is supportedon suitable supporting legsk I3, which are braced by means of suitable leg braces The hinged sections, I I are mountedon the extremities of the base section lll'uponsuitable hinge pins I4 and may ybeY clamped together at 'their topsto complete the circular mold by means of a threaded clamp rbar'` I5 Awhich is hinged in an upstanding ear 58,-on one of the sectionsI l, on a` suitable'hinge" pin. I 6. Thebar I5 drops into a receiving notch in'a similar ear'59 on'the other section into" which it is clamped by means of a'clamping nut 11.". By'tightening the lclamp.- 'ing' nutv I'I, the two sections may be 'rigidly clamped together.v j f f f j vWhen theclamp bar is released, theztwo'secf tions II may be swungA away from each other about the axisof the hingev pins I4,`as shown in broken line in Fig; 1.1"I'heamount of outward vmovement of these sections is limited by: means of stop bars I8 which'are secured atone of their extremities to the section I0 andare provided with slotted openings I9 for receiving pins 20 fixed to the' hinged sections II. When the pins 20 reach the extremities of the openings I9, outward movement of the sections` II isstopped.

Each of-.the sections I I is providedwith a .cushionin'g bracket 2| from each of which a pull bolt 22 is suspended. VThepull bolts pass through, fixed .brackets 23onthe section I0. The, pull 'bolts '22 are constantly'pulled downwardly by means of helical compression'v springs 24.1 `The springs act to cushion 'the' closing action of the two hinged housing sections I I and to prevent them `from falling together with damaging force. A resilient cushion member-v 25 surrounds veach pul1bolt5 Thus it can be seen that as the sections II .move inwardly, a portion of their weight will be absorbed by the bolts 22 to allow them to come gently together. `When the sections move` outwardly, they cometo rest on the cushion members 25.' The springs 24 also assist the operator lin opening the sectionI I.

A pry boss 2'6 projects from each of the sections l l adjacent to the top thereof to allow a pry bar to be inserted therebetween to pry the two sections apart after the retreading operation has been completed.

Each section of the housing is provided with an arcuate heating bar 28 which is resiliently mounted between guide lugs 29 onits inner surface. The heating bars Z8 are formed ci a metal having a high thermal'conductivity, such as aluminum, and each carries an imbedded electrical element 3Q, such as a Calrod, from which it derives its heat. The Calrod is inset'in a groove in the inner face of the heating bar so as to be exposed to the inner surfacethereof. The rods are locked in the grooves by indenting the edges of the latter as shown at 68. The current to the heating elements Vis conveyed across Vthe hinge points of the adjacent sections through suitable exible conduits 3 I.

VThe actual molding of the tire tread is accomplished by means of a sectional matrix ring 32. The ring 32 is formed in three sections fitting the sections I!! and ll of the housing. Theback of each matrix ring section rests on the lugs 29 in the housing sections and is locked in place therein by means of set screws 33 accessible from the exterior .of the housing. The inner face of each matrix ring section provides the mold for the desired -tire tread design. The ring: sections are quickly and easily removable by simply loosening the set screws 33 so that mold sections of any desired'isize `or design can be quickly and easily placed in the device.

l, The heating bars 28 are resiliently mounted between the guide lugs upon suitable springs Til vandl are each held in place against the action of the Ysprings by means of ra pair of .retaining v.b'olts `1l i'extending through the sections l0 and Il. `The bolts. 1l of `each -pair are -arrangedin parallel relation'so as to allow, free radial movementfoi the bars-28 Without binding. The bolts "Il are soadjusted as to allowthe bars to normally project inwardly `beyond the `tops ofgthe lugs 29,

as 'shown in Fig. 5. Thus when the matrix rings are resting on the tops of the lugs 29 the heating -bars willfbe frcedlinto contact'therewit-h under 'the'iniiuence'of the springs 13. The .Contacting arcuate .surfaces of the heating bars 2-8 and the matrixirings'f32 are accuratelymachined to hold them'in "uniform contact over their-entire vareas fs'o "that a uniform transference of heatis obtalne'd, to the 'matrix rings 32 throughout the entire circumference of the mold. All l.contraction and expansion under the influenceof heat israc- Vc'ommc'id'ated bythe springs 'lll without effecting the contactbe'tween the bars` 28 and the -matrix rings. vThelho'using sections I0 and H, are entirely open,'through Ventilating openings 55, and theydo not `contact lthe matrix rings so thatv free circulation of air is vallo-wedthroughout the entire housing-so that uniform heating of the matrix results withoutun'due heating oi the housing.

, Since the only contactbetween the matrix rings `32fand the housing is at the `tops ofthe lugs 29, it is'` not v'necessary to machine the entire inner 'circumference of the housing. *Only Vthe tops of the 'lugs n'eedto be machined. This reduces vmanufacturing cost'and reduces heat loss to the housl The'entire tire casing is uniformly forced outwardly Yagainst 'the matrix rings by means of a fm'e'chanical pressure device. `The llatter consists of a jack screw 35 which is detaclriably supported at its inner extremity in a xed bracket 3S and -38 adjacent its outer extremity for receiving the upper extremity of a connecting rod 42. The lower extremity of the connecting rod 42 is hing- .edly mounted on a hinge pin 64 on the bracket frame 43 at a point outwardly from and above the'axis of the-hinge bolts 44.

The above construction operates as follows: As the hand wheel 39 is pulled outwardly, the bracket 31 will swing outwardly. This normally would swing the inner extremity of the jack screw 35 upwardlywhich would not be possible since it would strike the tire casing in the mold. This is prevented, therefore, by the action of the connecting rod 42 which tends to cause the inner extremity of the jack screw to follow a substantially level path until itleaves the 'mold and then swings it outwardly to the broken line pcsition of Fig. 4 Where it will befout of the way 'for removingand replacing the tire casings.

Outward movementof the bracket 31 is limited Yby means of projecting Vfeeti45 `formed on the position.

*When the hinged bracket 31 is swung upwardly, the connecting 4rod also actsv onth'e sleeve 38 to accuratelyV alignV the jack screw 35'w`ith its bearing position in the inner bracket 36. The jack screw terminates in a spool '21 which slips into the'bracket 3'6 and i'slockd therein by means of a set screw 41. Thespcl is 'rdtatably mounted on the jack screw so that' the set screw 'prevents axial withdrawal of the .jack screw butallows free rotation thereof.

The jack screw`35 nsupports-a mechanical expandi'ng Vdevice which is described 'more in detail in applic'ants prior Patent No.,2, 228,3`1`6. Briefly, this device comprises two nuts "48jthreaded onto oppositeextrer'riities o'the jack screw 35. The tl'ireads'.l on the latter are of opposite hand at the opposite vextremities so that "rotation of the jack screw'in one direction will 'separate the nuts Vv'43 and rotation in the other directionl will 'cause them to approacheach other.,

'iA circular series of pressure shoes' 52 surround the jack screw between the nuts 48. ."Each sho'e is hingedly secured to a fitting '5l `by means 'of Va hinge pin 63. The extremities 'of Ya pair of radial toggle arms 49 are hinge-din the tting lon jhmge pins 52. A toothedclip".63jis'jsecured to veach arm 49. The`clips fare"` provided"with interineshing gear teeth 50.v The'opposite"extremity `of onevtoggle arm of each pair 'is yconne'c'zted to one' of the nuts`48 andthe other arm is similarly'conn'ected 'to theother nut'48. Thus'when the nuts approach each other, the ttings'5l are forced outwardly, th'us 4expanding `the entire vseries of shoes. When the nuts 'are "separated from each other, Ithe shoes are drawninwardly toward the jack 'screwin overlapping relation.

vThev -shoes are curved to apprximatethe arc yof their expanded circumference and each shoe is in the, innervfac of 3a' resilient,V vperiygfieralv cushjion band 54. 'The band 54 is formed'from resilientcompressible and extensible material, such as ing intoy the matrix ringsv 32;"andwhen rotated a lin -the other' direction, will be contracted away itherefrom. The contraction can be extended'un- Atil' thefshoes 52 lie close to the jack screw 35, 'as gshown ^inthe broken line in Fig. .4, atwhich time the band 54 can be entirely removed Afrom fgItwwilljbe-noted thatone Vextremity of veach 1 o f'thevr shoes v52 vis inset vas. shown atV 69 tof'allow -themfto form a perfect circular alignment in theirY workingy diameter.rr` f V QA; dowel pin 6l iSpO'sitioned in'one Vof the secvtions Il so as to enter a dowel hole in the other sectionto accurately align the two sections when they are clampedtogether in the closed position. The extremities of the clamp screws 33 are pointed so as to enter countersunk depressions in the matrix rings to accurately locate and lock them in position. When the device is used for tire casings of smaller diameter, the matrix rings, of course, are of a smaller internal diameter than those illustrated, the diierence in size being taken up by increasing the thickness of a contact pad 34 which. may be formed on the back of the `ring sections. To save metals-and weight this pad may be formed hollow as illustrated, if desired. It is desired to call attention to the bearing construction in the fixed bracket 36 as illustrated in detail in Fig. '1. The stem of the set screw 41 is hollow at the point to receive a detent spring 65. The spring acts against a pointed detent head 66 which forms the extremity of the screw shank. A plunger 61 extends from the head 66 axially outward to project from the screw 41. The point of the detent head enters a peripheral receiving groove vin the spool 21 on the extremity of the jack shaft, and when the screw 41 is tightened against the head 66 the latter is locked in place in the groove. If the screw 41 is loosened however the head is retained in the groove only by the action of the spring 65, which acts to temporarily hold the jack shaft in place. This construction enables a single operator at the front of the device to withdraw and reinsert the extremity of the jack screw without danger of its falling from place until the screw 41 is tightened.

The hinged sections l I and the base section l are reinforced by means of suitable reinforcing ribs 56 and 51 to prevent distortion from the extreme pressures and temperatures placed thereon. While a speciiic form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent 1. In a tire retreading device of the type having an annular, vertically positionedmatrix mold for a tire tread, means for expanding said tread into said mold comprising: a fixed bracket extending to an axial position at one side of said mold; a hinged bracket extending to a similar '[6 uposition' at-th'e other side of said mold; a ja'ck screwirotatab'ly mounted in said hinged bracket dandfarrangedto be detachably received by said fixed bracket; and an annular expanding mech- 5 anism mounted on and surrounding said jack screw, said mechanism being operable by said vjack screw so that it may be swung into or away Vfrom said mold by swinging said hinged bracket.

vv2. In a tire retreading device of the type havingan annular, vertically positioned matrix mold 'for aatire tread, means for expanding said tread into said mold comprising: a iixedfbracket extending to an axial position at one side of said mold; a hinged bracket extending to a similar position at the other side of a said mold; a jack screw rotatably mounted in said hinged bracket vand arranged to be detachably received by said fixed bracket; an annular expanding mechanism rmounted on and surroundingv said jack screw,-

vent its withdrawal from said xed bracket until desired.

3. In a tire treading device of the type having an annular, vertically positioned matrix mold for a tire tread and a mechanical expanding device positioned within said mold, means for supporting said expanding device so that it can be swung from said mold comprising; a jack screw normally extending axially through said mold and supporting said expanding device; a first bracket fixed to and extending to an axial position at one side of said mold; a bearing in said bracket for removably receiving one extremity of said jack screw; a second bracket; means for hingedly mounting said second bracket so that it may be swung to an axial position at the other'side of said mold; and a second bearing in said second bracket permanently and rotatably supporting said jack screw so that when said second bracket is swung from its axial position said jack screw and said expanding device will be swung from said mold.

4. In a tire treading device of the type having an annular, vertically positioned matrix mold for a tire tread and a mechanical expanding device positioned within said mold, means for supporting said expandingA device so that itcan be swung from said mold comprising: a jack screw normally extending axially through said mold and 55 supporting said expanding device; a iirst bracket vfixed to and extendingl to an axial position at one side of said mold; a bearing in said bracket for removably receiving one extremity of said jack screw; a second bracket; means for hing- 50 edly mounting said second. bracket so that it y may be swung to an axial position at the other side of said mold; a second bearing in said second bracket permanently and rotatably sup-r A porting said jack screw so that when said sec- 06 ond bracket is swung from its axial position said jack screw and said expanding device will be swung from said mold, said second bearing being hingedly mounted'on said secondbracket;

and means for retarding the swinging movement of said bearing as said second bracket is swung from its axial position to initially retard the upswing of the free extremity of said jack screw.

5. In a tire treading device Kof the type having an annular, vertically positioned matrix mold for 76 a tire tread and a mechanical expanding deet; and-locking means engaging said spool to pre-Y vice positioned vwithin said mold, means for supporting said expanding device so that it can be 'swung from said mold comprising: a jack screw `normally extending axially through said mold and supporting said expanding device; a first bracket fixed to and extending to an axial posi- .tion at one side of said mold; a bearing in said bracket for removably receiving one extremity of said jack screw; a second bracket; .means for hingedly mounting said second bracket so that it may be swung to an axial position at the other side of said mold; a second bearing in said second bracket permanently and rotatably supporting said jack screw so that when said second bracket is swung from its axial position said jack screw and said expanding device will be swung from said mold, said second bearing being hingedly mounted Yon said second bracket;..a connecting rod extending from said second bearing eccentrically of the hinge point of the latter; and means for pivotally mounting the ex- .;tremity of said connecting rod on an axis ad- Ina tire treading `device ofthe type having an annular, vertically positioned matrix mold for a tire tread and a mechanical expanding device positioned within said mold, means for supporting said expanding device so that it can be swung from said mold comprising: .a jack screw normally extending axiallyvthrough said mold and supporting said expanding device; a rst bracket xed to and extending to anaxial position at one `side of said mold; a bearing in said bracket for removably receiving one extremity of said jack screw; a second bracket; .means for hingedly mounting said second bracket so that it may be swung to an axial position at the other side of said mold; a second bearing in said second bracket permanently and rotatably supporting said jacket screw so that when said second bracket is swung fromits axial position said jack screw and said expanding device will be swung from said mold; and releasable latching means for holding the yextremity of said .jack screwin said first bearing.

HAROLD V. JAMES. 

